So I was talking with a guy at work and he was telling be that beacuse of the 264 win mag is considered a "overbore" round that it will flatten the boat tails of all bullets so he only shoots flat base bullets?

I'm sure some one else has heard this or maybe seen it I dont know it was news to me I would like to here more as I have a barrled action sitting in the gun safe and was planning on using 140g VLDs.

I'm no genius, but I can almost bet my rifle that boat tails don't flatten due to pressure. Sounds like he had a bad go of it with BT bullets and has been able to tune flat base easier.

Tank

__________________
Matthew 7:13-14
"Enter through the narrow gate. For wide is the gate and broad is the road that leads to destruction, and many enter through it. [14] But small is the gate and narrow the road that leads to life, and only a few find it.

So I was talking with a guy at work and he was telling be that beacuse of the 264 win mag is considered a "overbore" round that it will flatten the boat tails of all bullets so he only shoots flat base bullets?

I'm sure some one else has heard this or maybe seen it I dont know it was news to me I would like to here more as I have a barrled action sitting in the gun safe and was planning on using 140g VLDs.

"overbore" doesn't mean high pressure. You can of course load any cartridge to give excessive pressure. That's dumb as doing so will damage the action. At reasonable pressures however an "overbore" cartridge will give reduced barrel throat life. Throat erosion takes place as the temperature of the surface of the metal in the barrel throat approaches the melting point of the barrel steel. That's primarily a a function of the bore diameter (normal) , the pressure (and hence the temperature) of the propellant gas (normal) , and the duration of the propellant flow which will be longer than cartridges with smaller case capacity. . I can't think of any reason a 264 WM should damage boattail bullets, and I've never seen evidence that it does in the bullets I shoot. I'm not saying it can't happen. I'd like to see photos of the recoverd bullets. It might tell if the damage was from pressure, jacket melting, or the result of impact at the target.

Some other "overbore" factory cartridges include the 223 WSSM,, the 7mm Rem Ultra Mag and the 30-378 Weatherby Magnum. There are a number of severely overbore wildcat cartridges. I own two 264 Win Mags. One is a pre-64 "featherweight" Win 70 with a 22" barrel The other is Rem 700 F Class target rifle with a 28" Pac-Nor heavy barrel. They are as different as night and day in their characteristics.

The only thing wrong with overbore cartridges is reduced barrel life. Why own an overbore rifle? It's because they can have superior performance in windy conditions with low drag bullets. Smaller cartridges (or larger bores) are usually superior when wind deflection uncertainty is not the limiting accuracy factor. Personally I don't mind buying barrels occasionally to get high performance. Barrels are not the major expense of shooting a 264 Win Mag or a 223 WSSM or a 30-378 Wby. Ammunition is even if it's handloaded.